JP6321766B1 - Rubber elastic body formed with silver mirror film layer and method for producing the same - Google Patents

Abstract

A rubber elastic body on which a silver mirror film layer is formed, which can be easily formed by a coating method, has good appearance and adhesion of a silver mirror film layer, and has good appearance and adhesion of a silver mirror film layer. A manufacturing method thereof is provided. A rubber elastic body on which a silver mirror film layer according to one aspect of the present invention is formed includes an undercoat coating film formed on the surface of a rubber elastic body, and a silver mirror formed on the surface of the undercoat film. A film layer 13 and a top coat film 14 formed on the surface of the silver mirror film layer 13. The undercoat film 12 and the top coat film 13 are made of a main material containing a polyol component and poly It consists of an elastic polyurethane resin coating film formed with a curing agent containing an isocyanate component and having an elongation of 80% or more and 600% or less. [Selection] Figure 1

Description

  The present invention relates to a rubber elastic body on which a silver mirror film layer is formed and a method for producing the rubber elastic body, and in particular, a silver mirror film layer that can be easily formed by a coating method and has good appearance and adhesion of the silver mirror film layer. The present invention relates to a rubber elastic body and a manufacturing method thereof.

  Silver (Ag) has a high reflectance in the visible region and a beautiful metallic luster. When a silver mirror film layer is formed on a substrate such as a resin or metal, it exhibits a beautiful metallic luster. Therefore, it is expected to apply a silver mirror film layer to automobile interior parts and exterior parts, mobile phones, laptop computers, cosmetic containers, etc. . For example, automobiles are painted for the purpose of protecting the main materials of automobiles (in most cases, steel plates and plastic plates) and improving the aesthetics of automobiles. Compared to cars with the same shape and performance, a beautifully painted car looks better and increases its value as a product. Metallic paint has a high-class metallic texture, and when you look at the exterior of the car, the color looks different depending on the angle at which you look at the car, and it can give a sharp shape to the shape of the car. popular. Aluminum flakes are often used as metallic luster for car metallic paint. Such metallic coating is also used in other products, and the use of silver as a bright material or a mirror surface forming film is being studied in high-grade products.

  Conventionally, silver mirror plating by silver mirror reaction using an ammoniacal silver nitrate solution is well known as a method for forming a silver mirror film on a substrate. Silver mirror plating using this ammoniacal silver nitrate solution may cause plating-induced chalking (also known as whitening or shining) in the silver mirror film, cracks in the silver mirror film, and the film thickness of the silver mirror film may not be uniform. In some cases, the color of the silver mirror surface (metallic luster) may become uneven due to variations in the aggregation of silver nanoparticles. Furthermore, this silver mirror plating may cause the part that does not need to be silver mirror plated to be silver mirror plated, which has a high defect rate, and the formed silver mirror film surface is easily peeled off from the surface of the substrate or the like. There is also a problem.

  In order to solve the problem of silver mirror plating using such an ammoniacal silver nitrate solution, it is known to use a silver compound complex in which an amine compound or an ammonium carbamate compound is coordinated instead of ammonium as a silver compound complex. Yes. For example, Patent Document 1 (Japanese Patent No. 5610359) discloses a first complex in which an ammonium carbamate compound is coordinated to a silver atom of a silver compound in an alcohol solvent, and an amine compound to the silver atom of the silver compound. And a reducing agent, and the mixing ratio of the first complex and the second complex is 6: 4 to 8: 2 in terms of the molar ratio of silver atoms. The invention of a silver mirror film layer forming composition liquid, a method of producing a silver mirror film layer forming composition liquid, and a method of forming a silver mirror film coating surface is disclosed.

  Similarly, Patent Document 2 (Japanese Patent No. 5243409) discloses one or more silver compounds of the following chemical formula 1 and one or more ammonium carbamate or ammonium carbonate compounds selected from the following chemical formulas 2 to 4. A reflective film coating solution composition comprising a silver complex compound obtained by reacting with a compound is disclosed.

（式中、Ｘは、酸素、硫黄、ハロゲン、シアノ、シアネート、カーボネート、ニトレート、ニトライト、サルフェート、ホスフェート、チオシアネート、クロレート、パークロレート、テトラフルオロボレート、アセチルアセトネート、カルボキシレート、及びこれらの誘導体から選択される置換基であり、ｎは、１〜４の整数であって、Ｒ１乃至Ｒ６は、互いに独立して、水素、Ｃ１〜Ｃ３０の脂肪族や脂環族アルキル基、アリール基又はアラルキル（ａｒａｌｋｙｌ）基、官能基が置換されたアルキル及びアリール基、ヘテロ環化合物基と高分子化合物及びその誘導体から選択される置換基であって、但し、Ｒ１〜Ｒ６が全て水素である場合は除く。）

Wherein X is from oxygen, sulfur, halogen, cyano, cyanate, carbonate, nitrate, nitrate, sulfate, phosphate, thiocyanate, chlorate, perchlorate, tetrafluoroborate, acetylacetonate, carboxylate, and derivatives thereof. N is an integer of 1 to 4, and R1 to R6 are independently of each other hydrogen, a C1 to C30 aliphatic or alicyclic alkyl group, an aryl group, or an aralkyl ( aralkyl) groups, alkyl and aryl groups substituted with functional groups, heterocyclic compound groups and substituents selected from polymer compounds and derivatives thereof, except when R1 to R6 are all hydrogen. )

  Furthermore, a method of once forming silver nanoparticles and then forming a silver mirror film layer as a coating film is also known. For example, in Patent Document 3 (Japanese Patent No. 5950427), a polystyrene glycol having a styrene-maleic anhydride resin structure in an alcohol solvent and a part of the maleic anhydride being a terminal hydroxyl group or a terminal amino group is disclosed. Using an alcohol solution in which at least one silver compound selected from silver oxide and silver carbonate is dispersed while dissolving a polymer dispersant having an acid value of 150 or less, which is modified with alkylene glycol, By irradiating the alcohol solution with ultrasonic waves, a coating solution for forming a silver mirror film layer consisting of an alcohol solution in which silver nanoparticles are dispersed is prepared, and this silver mirror film layer forming composition solution is spray-coated on the surface of the object to be coated. A method of forming a silver mirror film layer by drying at room temperature is shown.

  By the way, these silver mirror film layers are generally formed on a hard surface such as a metal surface or a plastic surface as a base material. A silver mirror film layer can be formed on such a hard surface not only by the chemical plating method described above but also by a vapor deposition method or a sputtering method. However, the method of forming a silver mirror film layer on the surface of a rubber elastic body has been put into practical use because there are problems such as the occurrence of cracks and poor adhesion due to inadequate followability to deformation of the silver mirror film layer. Not in.

  The method itself for forming the silver mirror film layer on the rubber elastic body surface is already known. For example, in Patent Document 4 (Japanese Patent Laid-Open No. 06-343690), a rubber is subjected to a surface cleaning treatment using a reducing agent solution, then treated with glyoxal, then treated with an ammoniacal silver nitrate solution, and further if necessary. A method for producing an antibacterial rubber having a rubber surface coated with silver by treatment with an aqueous metal chloride solution is shown.

  Further, in Patent Document 5 (Japanese Patent Laid-Open No. 2010-110701), a soft resin layer containing a resin component and an aggregating agent that neutralizes the zeta potential of the silver nanocolloid and a soft resin layer formed on the soft resin layer are formed. It has a surface layer coated or printed using a printing ink containing a resin component and silver nanocolloid, and the silver nanocolloid is aggregated and segregated on the surface of the underlayer by selectively aggregating the silver nanocolloid. In addition, a method for forming a silver metal glossy thin film that can provide a desired silver metal gloss layer and solve the problem of peeling and missing even for a flexible member is shown.

Japanese Patent No. 5610359 Japanese Patent No. 5243409 Japanese Patent No. 5950427 Japanese Patent Laid-Open No. 06-343690 JP 2010-110701 A

  The manufacturing method of the antibacterial rubber disclosed in Patent Document 4 employs a silver mirror plating method using an ammoniacal silver nitrate solution, and thus has the various problems described above. In addition, it is difficult to immediately adopt a method for forming a silver mirror film layer, and there is a problem in deformation followability of the obtained silver mirror film layer. In addition, the method for forming a silver metallic glossy thin film disclosed in Patent Document 5 requires that the silver colloid be aggregated and adsorbed on the underlayer. For example, both the underlayer and the surface layer have a thickness of 50 to 500 μm, preferably Is an extremely thick film of 100 to 300 μm. Therefore, a large amount of expensive silver colloid is required, which is economically impractical. Also, the thick coating process is complicated, and a liquid layer containing a flocculant is laminated on the surface layer, or application of an electric field to the surface layer is recommended, and there is a problem in workability. In addition, the silver metal glossy thin film obtained by the method disclosed in Patent Document 5 also has a problem in deformation followability.

  On the other hand, as a method for forming a silver mirror film layer on the surface of a rubber elastic body, a method for forming a silver mirror film layer from a silver compound complex solution coordinated with an amine compound or an ammonium carbamate compound shown in Patent Documents 1 to 3 above. Once the silver nanoparticle is formed and then the silver mirror film layer is formed as a coating film, a silver mirror film layer that is more uniform and has a higher reflectivity than that obtained by silver mirror plating using an ammoniacal silver nitrate solution is obtained. Excellent effect. However, even if these methods are employed to form a silver mirror film layer on the surface of the rubber elastic body, there is a problem that the obtained silver mirror film layer has low deformation followability.

  The present invention has been made to solve the problems in forming a silver mirror film layer on the surface of the rubber elastic body of the conventional example described above. That is, the present invention provides a silver mirror film by reviewing the physical properties of the undercoat paint formed on the surface of the rubber elastic body and the top coat paint formed on the surface of the silver mirror film layer, and further reviewing the composition of the silver mirror film layer forming composition. An object is to provide a rubber elastic body on which a silver mirror film layer is formed and a method for producing the rubber elastic body, in which the deformation followability of the layer is good, the appearance and the adhesion of the silver mirror film layer are also good.

The rubber elastic body in which the silver mirror film layer of the first aspect of the present invention is formed is an undercoat film formed on the surface of the rubber elastic body, a silver mirror film layer formed on the surface of the undercoat film, and the above A rubber elastic body having a silver mirror film layer having a top coat film formed on the surface of the silver mirror film layer, wherein the silver mirror film layer contains colloidal silica whose surface is urethanized with an elastic polyisocyanate. The undercoating film and the top coating film are formed of a main material containing a polyol component and a curing agent containing a polyisocyanate component, and each elongation is 80% or more and 600% or less. It consists of a polyurethane resin coating film.

According to the rubber elastic body in which the silver mirror film layer of this aspect is formed, the elongation rate of the undercoat film and the topcoat film is good, and the colloidal whose surface is urethanized with an elastic polyisocyanate in the silver mirror film layer since silica is contained, the silver mirror film layer also well that Do is good deformability as it, adhesion and between the silver mirror film layer and the top coat of the silver mirror film layer and the undercoating film is Since each improves and the buffering effect between silver particles becomes good, the deformation follow-up property of the silver mirror film layer is improved, and a silver mirror film layer having good physical properties is formed. As a result, a rubber elastic body on which a silver mirror film layer excellent in mirror surface appearance, adhesion, bending resistance, cold bending resistance, cold repeatability and the like is formed can be obtained. In addition, the elongation rate in this invention shows the numerical value measured by the method based on JISK7311. Moreover, when the elongation rate of a coating film is less than 80%, the followability of the coating film with respect to a deformation | transformation of a base material will fall, a crack will be produced, or adhesiveness between base materials will come to fall. Further, when the elongation percentage of the coating film exceeds 600%, the coating film is too soft and easily damaged, and the chemical resistance is also lowered, so that the mirror surface appearance is deteriorated particularly by a solvent attack of the top coating material. The elongation ratio of the more preferable undercoat film and topcoat film is 100% or more and 500% or less.

  Moreover, according to the rubber elastic body in which the silver mirror film layer of such an aspect is formed, the elastic polyurethane resin coating film has good transparency and is excellent in heat resistance, solvent resistance, acid resistance and alkali resistance. In addition to the above-described characteristics, a rubber elastic body on which a silver mirror film layer having excellent heat resistance, solvent resistance, acid resistance, and alkali resistance is formed can be obtained.

  Further, the rubber elastic body in which the silver mirror film layer of the second aspect of the present invention is formed is a reaction comprising a polycaprolactone polyol in the main material in the rubber elastic body in which the silver mirror film layer of the first aspect is formed. A characteristic softener is contained.

  According to the rubber elastic body in which the silver mirror film layer of this aspect is formed, the elongation of the elastic polyurethane resin coating film forming the undercoat film or the topcoat film can be changed by changing the content ratio of the reactive softener in the main material. It becomes possible to control the rate appropriately to an optimal value.

  The rubber elastic body formed with the silver mirror film layer according to the third aspect of the present invention is the rubber elastic body formed with the silver mirror film layer according to the second aspect, wherein the content ratio of the reactive softening agent is the main content. It is 5-10 mass parts with respect to 100 mass parts of materials, It is characterized by the above-mentioned.

  According to the rubber elastic body in which the silver mirror film layer of this aspect is formed, the elongation percentage of the elastic polyurethane resin coating film forming the undercoat film or the topcoat film is appropriately controlled within the range of 80% to 600%. Will be able to. If the content of the reactive softener in the main material is less than 5 parts by mass, the elastic polyurethane resin coating film forming the undercoat film or the topcoat film becomes hard as the content ratio decreases. The elongation is less than 80%. In addition, when the content ratio of the reactive softener in the main material exceeds 10 parts by mass, the content ratio of the polyol component, which is a main component for coating film formation, decreases as the content ratio increases, so that the elastic polyurethane resin The strength of the coating film decreases.

  Moreover, the rubber elastic body in which the silver mirror film layer of the 4th aspect of this invention was formed is a rubber elastic body in which the silver mirror film layer of any one of the 1st-3rd aspect was formed, The said hardening | curing agent is elastic. Type polyisocyanate.

  According to the rubber elastic body in which the silver mirror film layer of this aspect is formed, the elongation percentage of the elastic polyurethane resin coating film forming the undercoat film or the topcoat film can be controlled to an appropriate value as appropriate. It becomes like this. In such an embodiment, the reactive softener may be contained in the main material of the polyurethane resin coating film, and in that case, the content ratio of both the reactive softening agent and the elastic polyisocyanate in the elastic polyurethane resin coating film is set. By appropriately changing, it becomes possible to easily control the elongation ratio of the elastic polyurethane resin coating film that forms the undercoat film or the topcoat film within an appropriate range.

  The rubber elastic body in which the silver mirror film layer according to the fifth aspect of the present invention is formed is the rubber elastic body in which the silver mirror film layer according to any one of the first to fourth aspects is formed. An adhesive primer layer is formed between the undercoat coating films.

  According to the rubber elastic body in which the silver mirror film layer of this embodiment is formed, even if the rubber elastic body is soft and the adhesion of the coating film is low, the rubber elastic body and the undercoating film are formed by the action of the primer layer for adhesion. Therefore, various physical properties of the rubber elastic body on which the silver mirror film layer is formed are good.

Furthermore, the method for forming a silver mirror film layer on the surface of the rubber elastic body according to the sixth aspect of the present invention includes:
Applying an undercoat paint to the surface of the rubber elastic body to form an undercoat film;
Applying a silver mirror film layer forming solution to the surface of the undercoat coating film to form a silver mirror film layer;
Forming a top coat film by applying a top coat to the surface of the silver mirror film layer;
A method of forming a silver mirror film layer on the surface of a rubber elastic body,
The one containing colloidal silica whose surface is urethanized with an elastic polyisocyanate in the silver mirror film layer forming liquid,
The undercoat paint and the top coat paint each include a main component containing a polyol component and a curing agent containing a polyisocyanate component, and the undercoat paint film and the top coat paint each have an elongation of 80% or more and 600% or less. A resin coating film is used.

The method for forming a silver mirror film layer on the surface of the rubber elastic body according to the seventh aspect of the present invention is the method for forming a silver mirror film layer on the surface of the rubber elastic body according to the sixth aspect. As the coating material, a material containing a reactive softener made of polycaprolactone polyol in the main material is used.

Moreover, the method for forming a silver mirror film layer on the surface of the rubber elastic body according to the eighth aspect of the present invention is the method for forming a silver mirror film layer on the surface of the rubber elastic body according to the seventh aspect, wherein the reactive softener The content ratio is 5 to 10 parts by mass with respect to 100 parts by mass of the main material.

The method for forming a silver mirror film layer on the surface of the rubber elastic body according to the ninth aspect of the present invention is the method for forming a silver mirror film layer on the surface of the rubber elastic body according to any one of the sixth to eighth aspects. A material containing elastic polyisocyanate is used as the curing agent.

The method for forming a silver mirror film layer on the surface of the rubber elastic body according to the tenth aspect of the present invention is the method for forming a silver mirror film layer on the surface of the rubber elastic body according to any of the sixth to ninth aspects. A primer layer for adhesion is formed on the surface of the rubber elastic body, and the primer layer is formed by applying the primer coating on the surface of the primer layer for adhesion.

According to the method of forming the silver mirror film layer on the surface of the rubber elastic body of the sixth to tenth aspects of the present invention, the rubber elastic body on which the silver mirror film layer of the first to fifth aspects of the present invention is formed, respectively. Can be manufactured.

  As described above, according to the present invention, the mirror appearance, adhesion, bending resistance, cold bending resistance, cold repeatability, and transparency are good, and heat resistance, solvent resistance, acid resistance and resistance are good. A rubber elastic body having a silver mirror film layer excellent in alkalinity is obtained.

It is a schematic cross section of the rubber elastic body in which the silver mirror film layer of this invention was formed.

  Hereinafter, the structure of the rubber elastic body in which the silver mirror film layer according to the present invention is formed and the manufacturing method thereof will be described in detail using various experimental examples. However, the following various experimental examples show examples for embodying the technical idea of the present invention, and are not intended to specify the present invention to those shown in these experimental examples. . The invention is equally applicable to other embodiments within the scope of the claims.

  The rubber elastic material that can be used in various embodiments of the present invention includes natural rubber (NR), butadiene rubber (BR), styrene butadiene rubber (SBR), isoprene rubber (IR), and other general-purpose rubbers. Other applications that require high performance such as heat resistance, oil resistance, and weather resistance include nitrile rubber (NBR), ethylene propylene rubber (EPDM), acrylic rubber (ACM), silicone rubber (VMQ), and fluoro rubber ( FKM) can be used. Moreover, there exists a thermoplastic elastomer (TPE) as a form which fills the gap between plastic and vulcanized rubber, and TPE such as polyolefin, polystyrene, polyester and polyurethane can also be used. Furthermore, it is applicable also to soft plastics, such as ethylene vinyl acetate (EVA) and soft vinyl chloride.

  As a one-component rubber paint, a main component is a graft rubber-based paint obtained by reacting rubber with a vinyl monomer, a one-component solvent-type paint such as a high-stretch polyurethane resin or an acrylic resin, acrylic rubber, and a polyurethane emulsion. One-component water-based paints are also in practical use. However, it is preferable to use a high-strength, high-elongation type polyol / polyisocyanate system or a polyurethane-based paint using a low molecular weight diamine as a chain extender from the viewpoint of performance such as weather resistance and durability against repeated deformation.

  As the two-component rubber paint, a two-component curing type high-performance polyurethane-based paint mainly composed of a polyurethane urea-based resin is desirable. As the polyol, polyester-based, polycarbonate-based, polyether-based, acrylic-based and fluorine-based polyols can be used. For the curing agent, the isocyanate derivative can be selected from standard types such as biuret type, isocyanurate type, adduct type, and elastic polyisocyanate (modified polyisocyanate obtained by urethanizing base polyisocyanate with polyether polyol). it can. What is necessary is just to use this hardening | curing agent properly from the point of the performance surface of a required coating film, or the point of enforcement. The use ratio of the polyol and the curing agent is determined by the OH number of the polyol and the NCO% of the curing agent, and is usually used in a molar ratio of 1 ± 0.2.

  Further, as the silver mirror film layer forming liquid, those prepared by the methods described in Patent Document 1 (Patent No. 5610359) and Patent Document 3 (Patent No. 5950427) were appropriately selected and used. Furthermore, the spray coating in each experimental example was unified so that all the same conditions were obtained, so that the coating thickness was substantially the same.

  A cross-sectional view of the rubber elastic body formed with the silver mirror film layer prepared in each experimental example is shown in FIG. The rubber elastic body 10 on which the silver mirror film layer was formed was formed on a rubber elastic body 11 as a base, an undercoat coating film 12 formed on the surface of the rubber elastic body 11, and a surface of the undercoat coating film 12. A silver mirror film layer 13 and a top coat film 14 formed on the surface of the silver mirror film layer 13 are provided. Hereinafter, the rubber elastic body 11, the undercoat coating film 12, the silver mirror film layer 13, and the top coating film 14 will be specifically described mainly by the manufacturing method for each experimental example.

[Experimental Example 1]
(Undercoat)
20 parts by mass of butyl acetate was uniformly mixed with 80 parts by mass of acrylic polyol resin (Cotax LH601, solid content 50%, OH number 20, Toray Fine Chemical Co., Ltd.). Furthermore, 10 parts by mass of polycaprolactone triol (Placcel 308, Daicel Organic Synthesis Company) as a reactive softening agent, 0.01 parts by mass of dilauric acid-di-n-butyltin as a curing catalyst, leveler (BYK300, Big Chemie Japan) was added and mixed in an amount of 0.2 parts by mass to prepare a base material for an undercoat. Next, adduct type polyisocyanate curing agent (Coronate HL, solid content 75%, NCO 12.3-13.3%, Nippon Polyurethane Industry Co., Ltd.), ratio of main agent: curing agent = 100: 10 (mass ratio) And diluted with thinner and spray-coated on a black natural rubber sheet. Subsequently, it forcedly dried at 90-100 degreeC for 40 minutes, and obtained the natural rubber sheet in which the primer coating film was formed.

(Silver mirror film layer)
A silver mirror film layer forming solution was prepared by the method described in [Experimental Example 1] of Patent Document 3 (Patent No. 5950427). That is, 4 g of Disperbyk 2015 (nonvolatile content 40%, acid value 10, BYK) as a polymer dispersant was dissolved in 100 g of 2-propanol (isopropyl alcohol), and 25 g of silver oxide powder was suspended. The acid value of the non-volatile content of the polymer dispersant is 25, and the content ratio of the polymer dispersant is (4 × 0.4 / 25) × 100 = 6.4% by mass ratio with respect to silver oxide. . Disperbyk 2015 has a styrene-maleic anhydride resin structure, and part of this maleic anhydride is modified with polyalkylene glycol having a terminal hydroxyl group.

  Subsequently, this suspension was irradiated at 20 KHz at room temperature of 15 to 17 ° C. for 2 hours using an ultrasonic device H3 650 (manufactured by Kawaji Re-Machinery). Next, it filtered with a 1 micrometer filter and the brown silver nanoparticle dispersion liquid was obtained. This silver nanoparticle dispersion was diluted 4-fold with ethyl alcohol, spray-coated, and dried at room temperature for 1 hour to obtain a natural rubber sheet having a silver mirror film layer formed on the undercoat film.

(Top coat)
Spray coating is performed using the undercoating paint of Experimental Example 1 as it is as an overcoating paint, followed by drying at 90 to 100 ° C. for 40 minutes to form an undercoating film, a silver mirror film layer and an overcoating film on the surface of the natural rubber sheet. A silver mirror film layer-forming sample of Experimental Example 1 was obtained.

[Experiment 2]
(Undercoat)
An acrylic polyol resin (Cotax LH601) was uniformly mixed with 80 parts by mass of 20 parts by mass of butyl acetate. Next, 0.01 parts by mass of dilauric acid-di-n-butyltin and 0.2 parts by mass of a leveler (BYK300) were added and mixed as a catalyst to prepare a base material for an undercoat paint. Next, an elastic polyisocyanate curing agent (Duranate E405-70B, solid content 70%, NCO 6.2%, Asahi Kasei Co., Ltd.) is mixed so that the main agent: curing agent = 100: 15 (mass ratio). It was diluted with thinner and spray-coated on a black natural rubber sheet. Subsequently, it forcedly dried at 90-100 degreeC for 40 minutes, and obtained the natural rubber sheet in which the undercoat film was formed.

(Silver mirror film layer)
The silver mirror film layer was formed in the same manner as in Experimental Example 1.

(Top coat)
Experimental Example 2 An experiment in which an undercoating film, a silver mirror film layer, and an overcoating film were formed on the surface of a natural rubber sheet after spray coating using the undercoating paint as it was as an overcoating paint and then drying at 90 to 100 ° C. for 40 minutes. The silver mirror film layer formation sample of Example 2 was obtained.

[Experiment 3]
(Undercoat)
An elastic polyisocyanate curing agent (Duranate E405-70B) is mixed with the main component of the undercoat similar to Experimental Example 1 so that the main component: curing agent = 100: 20 (mass ratio), and diluted with thinner. Sprayed on a black natural rubber sheet. Subsequently, it forcedly dried at 90-100 degreeC for 40 minutes, and obtained the natural rubber sheet in which the undercoat film was formed.

(Silver mirror film layer)
The silver mirror film layer was formed in the same manner as in Experimental Example 1.

(Top coat)
Experimental Example 3 An experiment in which an undercoat paint, a silver mirror film layer, and a top coat film were formed on the surface of a natural rubber sheet after spray coating using the undercoat paint as it is as an overcoat paint and then drying at 90 to 100 ° C. for 40 minutes. A silver mirror film layer-forming sample of Example 3 was obtained.

[Experimental Example 4]
(Undercoat)
40 parts by mass of butyl acetate was uniformly mixed with 60 parts by mass of a polycarbonate polyol resin (Duranol T5652, solid content 100%, OH number 51 to 61, Asahi Kasei Chemicals Corporation). Furthermore, 6 parts by mass of polycaprolactone triol (Placcel 308) as a reactive softening agent, 0.02 parts by mass of dilauric acid-di-n-butyltin as a catalyst, and 0.2 parts by mass of a leveler (BYK300) were added and mixed. The main component of the undercoat paint was prepared. Next, biuret type polyisocyanate (Duranate 24A-100, solid content 100%, NCO 23.5%, Asahi Kasei Co., Ltd.) is used as a curing agent at a ratio of main agent: curing agent = 100: 10 (mass ratio). The mixture was mixed, diluted with thinner, and spray-coated on a black butyl rubber sheet. Subsequently, it was forcibly dried at 90 to 100 ° C. for 40 minutes to obtain a butyl rubber sheet on which an undercoat coating film was formed.

(Silver mirror film layer)
A silver mirror film layer forming solution was prepared by the method described in [Experimental Example 1] of Patent Document 1 (Japanese Patent No. 5610359). That is, to a solution obtained by mixing 10.0 g of 2-propanol (isopropyl alcohol) (Daishin Chemical Co., Ltd.) with 4.16 g of 2-ethylhexyl ammonium 2-ethylhexyl carbamate, silver oxide (Ag ₂ O) (Ishifuku Metal) 2.1 g of Kogyo Co., Ltd. was added and stirred at room temperature for 2 hours. This solution was initially a black suspension, but eventually became a 2-propanol solution containing 2-ethylhexylammonium 2-ethylhexylcarbamate silver oxide complex which became cloudy white. The component which became grayish white is unreacted silver oxide particles, and 2-ethylhexylammonium 2-ethylhexylcarbamate silver oxide complex is in a state dissolved in 2-propanol. Thereafter, silver oxide precipitated in 2-propanol solution containing 2-ethylhexylammonium 2-ethylhexylcarbamate silver oxide complex was removed by filtration.

  Separately, in a solution obtained by mixing 6.03 g of 2-propanol (Daishin Chemical Co., Ltd.) with 1.93 g of n-butylamine (Wako Pure Chemical Industries, Ltd.), 0. 9 g was added and stirred at room temperature for 30 minutes to prepare an n-butylamine silver oxide complex. This n-butylamine silver oxide complex became a black suspension in 2-propanol, and then settled without dissolving in 2-propanol.

  The 2-propanol solution in which the 2-ethylhexylammonium 2-ethylhexylcarbamate silver oxide complex prepared as described above was dissolved and the 2-propanol solution in which the n-butylamine silver oxide complex was suspended were mixed and stirred. The mixture gradually became a gray suspension and then became a clear solution. Next, 2.33 g of N, N-dimethylaminoethanol (Wako Pure Chemical Industries, Ltd.), which is a reducing agent that does not show a reducing action at room temperature but shows a reducing action at a temperature exceeding room temperature, is added to this mixed solution. The composition liquid for silver mirror film layer formation which consists of a liquid for silver oxide complexes of Experimental Example 4 was prepared by adding 2-propanol to a total amount of 30 g.

  This silver mirror film layer-forming composition solution was spray-coated on the surface of the butyl rubber sheet of Experimental Example 4 which was diluted 3-fold with 2-propanol to form an undercoat and dried at 80 to 90 ° C. for 30 minutes to undercoat A butyl rubber sheet having a silver mirror film layer formed on the coating film was obtained.

(Top coat)
Experimental Example 4 An experimental example in which an undercoating film, a silver mirror film layer, and an overcoating film were formed on the surface of a butyl rubber sheet after spray coating using the undercoating paint as it was as the top coating, and then drying at 90 to 100 ° C. for 40 minutes. 4 silver mirror film layer formation samples were obtained.

[Experimental Example 5]
(Top coat)
Olefin rubbers such as ethylene propylene rubber (EPDM), thermoplastic elastomers such as olefin thermoplastic elastomer (TPO), soft plastics such as ethylene-vinyl acetate copolymer resin and soft polypropylene resin (PP) are difficult to adhere. And one coat is difficult. As a countermeasure, various primers are commercially available, but it is preferable to use a modified polyolefin-based adhesion primer. In Experimental Example 5, a modified polyolefin-based adhesion primer was applied to the surface of the EPDM material, and a silver mirror film layer-forming sample of Experimental Example 5 in which an undercoat film, a silver mirror film layer, and a topcoat film were formed on this surface was prepared. .

  A primer for adhesion was prepared by adding 50 parts by mass of toluene to 100 parts by mass of a modified polyolefin-based primer (Unistor P-401, solid content 8%, Mitsui Chemicals, Inc.). This adhesion primer was spray-coated on the surface of a black natural rubber sheet similar to that used in Experimental Example 3, and the primer coating prepared in Experimental Example 3 was applied after drying at room temperature for 10 minutes. Subsequently, it forcedly dried at 90-100 degreeC for 40 minutes, and obtained the EPDM sheet in which the primer coating film was formed.

(Silver mirror film layer)
The silver mirror film layer was formed in the same manner as in Experimental Example 4.

(Top coat)
The undercoat paint of Experimental Example 3 was used as it was as an overcoat paint, and after spray coating, it was dried at 90 to 100 ° C. for 40 minutes. The primer layer, the undercoat film, the silver mirror film layer and the overcoat film were adhered to the surface of the EPDM sheet. A silver mirror film layer-forming sample of Experimental Example 5 was obtained.

[Experimental Example 6]
(Undercoat)
In the same manner as in Experimental Example 3, a natural rubber sheet on which an undercoat coating film was formed was obtained.

(Silver mirror film layer)
Elastic polyisocyanate (Duranate E405-70B) with respect to 100 parts by mass of organic solvent-dispersed colloidal silica (average particle size 10-15 nm, dispersion medium methyl isobutyl ketone (MIBK), solid content 30%, Nissan Chemical Industries, Ltd.) 3 parts by mass was added and heated at 60 to 70 ° C. for 5 hours while stirring in a nitrogen gas stream. After the completion of the reaction, the mixture was aged at 25 ° C. to 30 ° C. for 24 hours to obtain colloidal silica whose surface was urethanized. This reaction is considered to be a urethanization reaction between the SiOH group on the nanosilica surface and the polyisocyanate, as shown in the following reaction formula.
_{-SiO 2 -OH + OCN ... R ...} NCO →
_{-SiO 2 -COONH ... R ... HNOOC-} SiO 2 -

  Next, in the silver nanoparticle dispersion obtained in the same manner as in Experimental Example 1, this surface urethanized colloidal silica liquid was added and mixed in a non-volatile content ratio of 12% to obtain a brown nanosilver / urethanized silica. A composite particle dispersion was obtained. This nano silver / urethane-modified silica composite particle dispersion is diluted 4-fold with ethyl alcohol and spray-coated on the surface of a natural rubber sheet on which an undercoat film has been formed, and dried at room temperature for 1 hour. A silver mirror film layer was formed.

(Top coat)
Experimental Example 3 An experiment in which an undercoat paint, a silver mirror film layer, and a top coat film were formed on the surface of a natural rubber sheet after spray coating using the undercoat paint as it is as an overcoat paint and then drying at 90 to 100 ° C. for 40 minutes. The silver mirror film layer formation sample of Example 6 was obtained.

[Experimental Example 7]
(Undercoat)
In the same manner as in Experimental Example 3, a natural rubber sheet on which an undercoat coating film was formed was obtained.

(Silver mirror film layer)
In the silver mirror film layer, the colloidal silica whose surface was urethanized prepared in Experimental Example 6 was added to the silver oxide complex solution prepared in the same manner as in Experimental Example 4 in a non-volatile mass ratio with respect to the solid content of silver. 6% of the mixture was added and mixed to obtain a transparent silver complex / colloidal silica composite liquid having a urethane surface. This silver complex / colloidal silica composite liquid whose surface is urethanized is diluted 3-fold with 2-propanol and spray-coated on the surface of a natural rubber sheet on which an undercoat film has been formed, at 80 to 90 ° C. for 30 minutes. A silver mirror film layer was formed by drying.

(Top coat)
Experimental Example 3 An experiment in which an undercoat paint, a silver mirror film layer, and a top coat film were formed on the surface of a natural rubber sheet after spray coating using the undercoat paint as it is as an overcoat paint and then drying at 90 to 100 ° C. for 40 minutes. A silver mirror film layer-forming sample of Example 7 was obtained.

[Comparative example]
(Undercoat)
20 parts by mass of butyl acetate was added to 80 parts by mass of an acrylic polyol resin (Cotax LH601) and mixed uniformly with stirring. Further, 0.01 parts by weight of dilauric acid-di-n-butyltin and 0.2 parts by weight of leveler (BYK300) were added and mixed as a catalyst to prepare a base material for an undercoat paint. Next, an adduct type polyisocyanate curing agent (Coronate HL) was mixed at a ratio of main agent: curing agent = 100: 10 (mass ratio), diluted with thinner, and spray-coated on a black natural rubber sheet. Subsequently, it forcedly dried at 90-100 degreeC for 40 minutes, and obtained the natural rubber sheet in which the primer coating was formed. The undercoat film of this comparative example is a hard film because no reactive softener is blended as compared with the undercoat film of Experimental Example 1.

(Silver mirror film layer)
The silver mirror film layer was formed in the same manner as in Experimental Example 1.

(Top coat)
A comparative example in which the undercoat paint, the silver mirror film layer and the top coat film were formed on the surface of the natural rubber sheet after spray coating using the base coat of the comparative example as it was, followed by spray coating at 90 to 100 ° C. for 40 minutes. A silver mirror film layer-forming sample was obtained.

[Measurement of various physical properties]
About the silver mirror film layer formation sample of Experimental Examples 1-7 and the comparative example produced as mentioned above, it used for the measurement of various physical properties as shown below.
(1) Appearance price,
(2) Adhesion evaluation test,
(3) Elongation measurement,
(4) Bending resistance test,
(5) Cold bending resistance test,
(6) Cold and hot repeated adhesion test,
(7) Moisture resistance test,
(8) Heat resistance test (9) Solvent resistance test,
(10) An acid resistance test and an artificial sweat test were performed.
(11) Alkali resistance test.
The specific measurement methods and judgment criteria for each test are as shown below, and the results are summarized in Table 1.

(1) Mirror surface appearance evaluation:
In the silver mirror film layer on which the top coat surface was formed, when coloring failure, crater, crack blistering, and chalking could be visually observed, it was rated as x.

(2) Adhesion evaluation test:
Evaluation was performed according to JIS 5600-5-6 (2007). After applying a cutter knife vertically to the coating film and making a cut in a grid of 2 mm × 2 mm square (100 squares), an adhesive tape with an adhesive strength of 0.44 ± 0.05 kgf / mm was applied. The adhesion test which peels at the angle of a degree was done. As a result, the case where peeling of the coating film was not recognized was evaluated as “◯”, and the case where peeling was observed was evaluated as “X”.

(3) Elongation rate:
Conforms to JISK7311. Using a precision universal testing machine (Autograph AG-100KNG, manufactured by Shimadzu Corporation), an undercoating film of about 100 μm was subjected to the conditions of a focal distance of 20 mm and a tensile speed of 50 mm / min.

(4) Measurement of bending resistance:
A bending test was performed with a round bar of 23 ° C. and 10 mmφ for the number of times shown in (i) and (ii) below, followed by an adhesion test.
(I) Repeated bending 10 times (ii) Repeated bending 50 times

(5) Measurement of cold bending resistance:
After leaving at −30 ° C. for 5 hours, a 10 mmφ round bar was subjected to a bending test as shown in (i) and (ii) below, followed by an adhesion test.
(I) Repeated bending 10 times (ii) Repeated bending 50 times

(6) Cold and hot repeated adhesion test:
The adhesion evaluation test was conducted after three cycles of leaving at −30 ° C. for 2 hours and then leaving at 60 ° C. for 2 hours.

(7) Moisture resistance test:
After being accommodated in a constant temperature bath at 40 ° C. ± 1 ° C. and a relative humidity of 95% or more and allowed to stand for 100 hours, an adhesion test was conducted.

(8) Heat resistance:
After being left in a constant temperature bath at 80 ° C. ± 2 ° C. for 24 hours, an adhesion evaluation test was performed.

(9) Solvent resistance:
A load of 100 g / cm ² was applied to a cotton cloth containing petroleum benzine, and the coating film was rubbed 10 times to evaluate the surface condition of the coating film. The case where there was no abnormality was rated as ○, and the case where there was a scratch was rated as ×.

(10) Acid resistance:
0.2 ml of a 0.1N sulfuric acid aqueous solution was dropped on the coating surface, and the appearance was evaluated after being allowed to stand at 23 ° C. for 2 hours (spot test method).
Observed by visual observation, those in which no abnormality or blistering was observed in the appearance of the coating film were marked with ◯, and those in which the abnormality was recognized were marked with ×.

(11) Alkali resistance:
0.2 ml of 0.1N caustic soda aqueous solution was dropped on the coating surface, and the appearance was evaluated after being allowed to stand at 23 ° C. for 2 hours (spot test method).

[Consideration]
From the results shown in Table 1, the following can be understood.
First, the results of Experimental Example 1 and Comparative Example are examined.
The undercoat and topcoat used in Experimental Example 1 and Comparative Example (hereinafter sometimes referred to as “paint”) include acrylic polyol as the main material and adduct-type polyisocyanate as the curing agent. It is common in the point which forms a polyurethane resin coating film using things. However, the coating material of Experimental Example 1 is different in that the reactive softening agent polycaprolactone triol is further added as a main material, whereas the reactive softening agent is not added to the comparative coating material. doing. In addition, the adapt type polyisocyanate is generally used as a standard curing agent for forming polyurethane. In addition, both silver mirror film layers are formed by spray-coating silver nanoparticle dispersion liquid, and there is no difference in the formation method of a silver mirror film layer.

  Thereby, in the comparative example 1, the hard polyurethane resin coating film was obtained, and the elongation rate of this polyurethane resin coating film is as very small as 7%. On the other hand, in Experimental Example 1, since the main component of the paint is a compound containing polycaprolactone triol, which is a reactive softening agent, a soft polyurethane resin coating film is obtained. The elongation rate is 198, which is much larger than that of the comparative example. In both cases, the mirror surface appearance shows good results, but the silver mirror film layer-formed sample of Experimental Example 1 shows good results except for cold bending resistance (ii), whereas the comparative example In the silver mirror film layer-formed sample, not only the cold bending resistance (ii), but also the bending resistance (i) and (ii), the cold bending resistance (i), and the cold repeated adhesion test were inferior. The cold bending resistance (ii) is a harsh test in which the number of bendings is larger than the cold bending resistance (i). Therefore, from the comparison of the results of Experimental Example 1 and Comparative Example, both the undercoating film and the topcoating film made of a polyurethane resin coating film are soft and have a large elongation rate. It can be seen that various physical properties of the silver mirror film layer-formed sample on which the silver mirror film layer and the top coat film are formed are good.

Next, the results of Experimental Examples 1 to 3 will be examined.
The coating materials used in Experimental Examples 1 to 3 are common in that the materials containing acrylic polyol are used as the main materials. However, the paints of Experimental Example 1 and Experimental Example 3 are further added with polycaprolactone triol as a reactive softener in the main material, and the reactive softening is applied to the main material of the paint of Experimental Example 2. In addition, the coating material of Experimental Example 1 uses the adapter type polyisocyanate that is a standard curing agent as the curing agent, whereas the coating materials of Experimental Example 2 and Experimental Example 3 use the curing agent. Is different in that an elastic polyisocyanate is used. The elastic polyisocyanate is a polyisocyanate composition obtained by a urethanization reaction between a polyisocyanate and a polyalkylene glycol ether.

  That is, while the paint of Experimental Example 1 gives flexibility to the polyurethane resin coating film by the main material, the paint of Experimental Example 2 gives flexibility to the polyurethane resin coating film by the curing agent. Furthermore, the coating material of Experimental Example 3 gives flexibility to the polyurethane resin coating film by both the main material and the curing agent. In addition, both silver mirror film layers are formed by spray-coating silver nanoparticle dispersion liquid, and there is no difference in the formation method of a silver mirror film layer.

  As a result, a polyurethane resin coating film having an elongation of 198% was obtained in Experimental Example 1, a polyurethane resin coating film having an elongation of 283% was obtained in Experimental Example 2, and an elongation of 463% was obtained in Experimental Example 3. A large polyurethane resin coating film is obtained. The silver mirror film layer-formed samples of Experimental Examples 1 to 3 are all good except for cold bending resistance (ii). Based on the above results, the flexibility of the polyurethane resin coating film is imparted by the composition of the main material or by the composition of the curing agent. It turns out that the various physical properties of the silver mirror film layer formation sample in which the film layer and the top coat film are formed are good.

Next, the result of Experimental Example 4 will be examined.
Experimental Example 4 uses a butyl rubber sheet as a raw material, a material containing polycarbonate polyol and polycaprolactone triol as a reactive softener as a main material of a paint, and a material containing biuret type polyisocyanate as a curing agent. A resin coating film is formed. Butyl rubber is known as a rubber elastic body harder than natural rubber, and polyurethane paint containing polycarbonate polyol is known to provide a highly durable coating film with good characteristics. is there. In addition, biuret type polyisocyanate is generally used as a standard curing agent for forming polyurethane using polycarbonate polyol. Here, as a silver mirror film forming method, the silver oxide complex solution is formed by spray coating.

  Thereby, the obtained polyurethane resin coating film has an elongation of 89%, which is smaller than that of Experimental Example 1 and larger than that of Comparative Example. According to this silver mirror film layer-formed sample, good results were obtained except for the bending resistance (ii) and the cold bending resistance (ii). This is because, in the sample for forming a silver mirror film layer of Experimental Example 4, the elongation percentage of the coating film was smaller than that of Experimental Example 1, so that not only cold bending resistance (ii) but also bending resistance (ii) It is thought that the result was inferior. Note that the bending resistance (ii) is also a severe test in which the number of bendings is larger than the bending resistance (i).

Next, the result of Experimental Example 5 will be examined.
Experimental Example 5 uses an ethylene propylene rubber (EPDM) sheet as a raw material, uses a polycarbonate polyol and polycaprolactone triol as a reactive softener as a main material of a paint, and includes an elastic polyisocyanate as a curing agent. A polyurethane resin coating film is formed using a material. Since EPDM rubber is difficult to adhere, a modified polyolefin-based adhesion primer is applied to the surface, and an undercoat paint is formed on the surface. The paint used here is the same as the paint of Experimental Example 3, and the elongation percentage of the obtained polyurethane resin coating film is as large as 463% as in the case of Experimental Example 3. Here, as a silver mirror film forming method, the silver oxide complex solution is formed by spray coating.

  According to this silver mirror film layer-formed sample, good results were obtained except for cold bending resistance (ii), and substantially the same results as the silver mirror film layer-formed sample of Experimental Example 3 were obtained. This means that, regardless of the type of rubber elastic body as the material, if a good adhesion is maintained between the material and the undercoat paint, the surface of the rubber elastic body is coated with an undercoating film, a silver mirror film layer and an overcoating film. It can be seen that the various physical properties of the silver mirror film layer-formed sample on which the film is formed are good.

Next, the results of Experimental Example 6 and Experimental Example 7 will be examined.
It was found that the measurement results of cold bending resistance (ii) were inferior in the silver mirror film layer-formed samples obtained in Experimental Examples 1 to 5, but this was caused by the difference between the silver mirror film layer and the undercoat film or the topcoat film. This is considered to be caused by poor adhesion. Therefore, in Experimental Example 6 and Experimental Example 7, a solution in which urethanized colloidal silica prepared using organic solvent-dispersed colloidal silica was added to a silver mirror film layer forming solution was used. As the silver mirror film layer forming solution, a silver nanoparticle dispersion based on the method described in Patent Document 3 is used in Experimental Example 6, and a silver oxide complex solution based on the method described in Patent Document 1 is used in Experimental Example 7. Are used respectively. Other coating film forming methods are the same as those in Experimental Example 3.

  In the silver mirror film layer-formed samples obtained in Experimental Example 6 and Experimental Example 7, the elongation percentage of each polyurethane resin coating film is 463%, which is the same as that of Experimental Example 3, but the measurement result of cold bending resistance (ii) It can be seen that good measurement results are obtained. This measurement result shows that since the urethanized colloidal silica is added to the silver mirror film layer forming solution, both the undercoat film and the topcoat film are polyurethane resin films, It is considered that the adhesion between the silver mirror film layer and the top coat film was improved, and that the deformation followability of the silver mirror film layer was improved by the buffering action between the silver particles.

  Therefore, the measurement results of Experimental Example 6 and Experimental Example 7 are obtained by adding urethanized colloidal silica to the silver mirror film layer forming solution even in the case of the silver mirror film layer forming samples obtained in Experimental Examples 1 to 5. Cold bending resistance (ii) also suggests that good results will be obtained. In addition, since the difference in structure between the silver mirror film layer formation samples of Experimental Example 6 and Experimental Example 7 is only the silver mirror film forming method, the difference in the silver mirror film forming method does not affect the measurement results of various physical properties. I understand that.

  In preparing the urethanized colloidal silica, it is preferable to add the elastic polyisocyanate so as to have a ratio of 3 to 12 parts by mass with respect to 100 parts by mass of the organic solvent-dispersed colloidal silica. If the addition ratio of the elastic polyisocyanate is 3% by mass or less, the effect of the addition of the elastic polyisocyanate is small, and if the addition is 12% by mass or more, the storage stability of the urethanized colloidal silica liquid (urethanized silica sol liquid) is lowered. To do.

Here, from the measurement results of Experimental Examples 1 to 7 and Comparative Example 1, the elongation rate of the optimum coating film (undercoat film and topcoat film) is examined.
If the elongation percentage of the coating film is 80% or more from the results of Experimental Example 4 and Comparative Example, good results can be obtained except for the measurement results of bending resistance (ii) and cold bending resistance (ii). it is conceivable that. However, in Experimental Example 1, which is larger than the elongation percentage of the coating film of Experimental Example 4, the measurement result of cold bending resistance (ii) is not different from that of Experimental Example 4, but the measurement result of bending resistance (i) is good. Therefore, if the elongation percentage of the coating film is 100% or more, it is considered that good results in bending resistance (ii) can be obtained. In addition, when the elongation rate of a coating film exceeds 600%, since the damage property and mirror surface appearance of a coating film fall, it turns out that 80% or more and 600% or less are preferable, and 100% or more and 500% or less are more preferable.

  Moreover, from the measurement results of Experimental Examples 1 to 7 and Comparative Example 1, the elongation percentage of the coating film can be changed depending on the content ratio of the reactive softener in the main material, and the main material and the elastic polyisocyanate. It can be seen that it can also be changed by changing the mixing ratio. The ratio of the reactive softener contained in the main material is preferably 5 to 10 parts by mass with respect to 100 parts by mass of the main material. When the proportion of the reactive softener contained in the main material is less than 5 parts by mass, it becomes difficult to maintain the elongation within a desired range. Since the content ratio of the polyol component is less, the strength of the coating film is lowered.

10: Rubber elastic body on which a silver mirror film layer is formed 11: Rubber elastic body 12: Undercoat film 13: Silver mirror film layer 14: Top coat film

Claims (10)

Undercoat film formed on the surface of rubber elastic body,
A silver mirror film layer formed on the surface of the undercoat film, and
A top coat film formed on the surface of the silver mirror film layer,
A rubber elastic body in which a silver mirror film layer having
The silver mirror film layer contains colloidal silica whose surface is urethanized with an elastic polyisocyanate,
The undercoating film and the top coating film are formed from an elastic polyurethane resin coating film formed of a main material containing a polyol component and a curing agent containing a polyisocyanate component, each having an elongation of 80% or more and 600% or less. A rubber elastic body in which a silver mirror film layer is formed.   The rubber elastic body formed with a silver mirror film layer according to claim 1, wherein the main material contains a reactive softener made of polycaprolactone polyol.   The rubber elastic body having a silver mirror film layer according to claim 2, wherein a content ratio of the reactive softening agent is 5 to 10 parts by mass with respect to 100 parts by mass of the main material.   The rubber elastic body in which the silver mirror film layer according to any one of claims 1 to 3 is formed, wherein said hardening agent contains elastic type polyisocyanate.   The rubber elastic body having a silver mirror film layer according to any one of claims 1 to 4, wherein an adhesive primer layer is formed between the rubber elastic body and the undercoat coating film. Applying an undercoat paint to the surface of the rubber elastic body to form an undercoat film;
Applying a silver mirror film layer forming solution to the surface of the undercoat coating film to form a silver mirror film layer;
Forming a top coat film by applying a top coat to the surface of the silver mirror film layer;
A method of forming a silver mirror film layer on the surface of a rubber elastic body,
Using the silver mirror film layer forming liquid containing colloidal silica whose surface is urethanized with an elastic polyisocyanate,
The undercoat paint and the top coat paint each include a main component containing a polyol component and a curing agent containing a polyisocyanate component, and the undercoat paint film and the top coat paint each have an elongation of 80% or more and 600% or less. A method for forming a silver mirror film layer on the surface of a rubber elastic body, characterized by using a resin coating film. The silver coating film layer is formed on the surface of the rubber elastic body according to claim 6 , wherein the base coating material and the top coating material are those containing a reactive softening agent composed of polycaprolactone polyol in the main material. how to. 8. The silver mirror film layer is formed on the surface of the rubber elastic body according to claim 7 , wherein a content of the reactive softener is 5 to 10 parts by mass with respect to 100 parts by mass of the main material. how to. The method for forming a silver mirror film layer on the surface of a rubber elastic body according to any one of claims 6 to 8 , wherein an elastic polyisocyanate is used as the curing agent. The rubber elastic body adhesive primer layer is formed on the surface of, and forming the undercoat layer and the undercoat and is applied on the surface of the adhesive primer layer, any of the claims 6-9 A method of forming a silver mirror film layer on the surface of a rubber elastic body according to claim 1.

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